I've had to create a Google Group to allow Beta testers to join. If you PM or email (rik@plancd.com) me your email address I can add you to the group. There is no need to 'participate' in the group at all you just need to be a member to see the beta links in in the Chrome app store (the beta test won't cost you anything except your time). It will be a few weeks before there is anything to show but I thought I would collect testers early.